\documentclass[10pt,a4paper]{report}
\usepackage{pgfplots}
\pgfplotsset{compat=1.13}
\usepackage{pgfplotstable}
\begin{document}
\pgfplotstableread[col sep=space]{
x y w1 w2
1 1 2 4
2 2 1 3
3 3 4 2
4 4 3 1
}\data

\begin{tikzpicture}
\begin{axis}[]
\addplot[
    scatter,
    only marks,
    scatter src=explicit,
    visualization depends on=\thisrow{w2}\as\wtwo,
    scatter/@pre marker code/.append style={
        /tikz/mark size=\wtwo
    }
]
table[x=x,y=y,meta=w1]{\data};
\end{axis}
\end{tikzpicture}

\end{document}
